530 FLORA OF THE LARAMIE GROII'. 



Saporta (not of Heer) foiiud at Sezaiiue. These three Eocene localities 

 represent the highest and lowest Eocene, and fairly exhibit the degree 

 of hoinotaxy subsisting between these formations. 



The remaining six species that occur in the Laramie and the Eocene, 

 possess less force in this direction from the fact that they are all found 

 iu other and higher formations also. Most of them are plants that 

 are abundantly represented in nearly all tlie more recent deposits, such 

 as Taxudium Eurojxvttm, found all the way from the Middle Bagshot of 

 Bournemouth to the Pliocene of Meximieux, Fictcs tiliwfolia, Laurus 

 priiiii(/i'Hia, and Chinamomum lanceolatum, abundant in nearly all the 

 Oligoceue and Miocene beds of Europe. Qiiercun chhrophyUa occurs 

 iu the Mississippi Tertiary as well as at Skopau in Sachs-Thiiriugen, 

 and is also abundant in the Miocene, and Ficiis tlliafoUa is found in the 

 Green River formation at Florissant, Colorado. The only other species 

 belonging to this class is Goniopteris polypodioides, which occurs at 

 Monte Promina and in the Miocene of Kivaz. Alnus Kefersteinii, once 

 reported from Aix in Provence, is considered doubtful, and should prob- 

 ably be excluded from the list of Eocene plants, but it is found in the 

 American Eocene of both Florissant and Green River. Iu the Laramie 

 it is only known from the Evanston coal beds, and is most abundant 

 in the arctic Miocene of Alaska, Spitzbergen, etc., but it is also common 

 iu the Miocenes of Northern and Central Europe. 



This is all that can be said in favor of the Eocene character of the 

 Laramie flora, and wei'e it not capable of being further weakened, the 

 case might be regarded as somewhat stronger than that of the gen- 

 era; but there still remain manj' importaut considerations which affect 

 the legitimacy of some of these facts. For example, we have seen that 

 fourteen species altogether occur in the Laramie and the Eocene; but 

 the number occurring in the Laramie and formations higher than Eocene 

 is sixty-two. Thirty-flve of these are confined to the Laramie and Mio- 

 cene. Two ( Diplazium Miilleri and Fluhdlaria Zinkeni) are confined to the 

 Laramie and Oligocene, while twelve occur in Laramie, Oligoceue, and 

 Miocene strata. These species are by no means confined to those that 

 have only been found in the northern districts, but, as any one can see 

 by examining the table, they come largely from the typical beds, and 

 include such species as kSahal VcunpheUii, Salix integra, Betula gracilis, 

 Ficus asnrifolia, Rhamnus alntcrnoidcs, etc. 



It would certainly be very unsafe from this to argue that the lower 

 Laranne is Miocene. With such a vast flora as the Miocene, numbering 

 as it does (including the Oligocene Iteds) nearly 4,000 species, it is rea- 

 sonable to expect that as many Laramie forms as are found common to 

 the two formations (about l.J per cent.) should persist nearly unchanged 

 from one epoch to the other. As a matter of fact, a much larger per- 

 centage of forms thus persists where the two deposits occupy nearly the 

 same geographic area. Some four or five of the Laramie species are 

 still found in the living flora, most of I hem iu North America, un- 



